skeletal system introduction

functions of the skeletal system

1) support

2) storage of minerals and lipids

3) blood cell production: red marrow produces blood cells

4) protection

5) leverage: many bones function as levers

long bones

long and slender

* located in arm, forearm, thigh, leg, fingers, etc.

short bones

boxy

* examples: carpal bones and tarsal bones

flat bones

thin, flat bones

* examples: bones that form the roof of the skeleton, ribs, scapula

irregular bones

complex shapes

* examples: vertebrae, bones of the pelvis

sesamoid bones

generally small, flat, irregular shaped bones

* develop inside tendons and commonly located near joints
* example: patellar shape

sutural bones (wormian bones)

small, flat, irregular shaped bones

* located between flat bones of the skull

epiphysis

part of long bone; end of the long bone

diaphysis

part of long bone; long, tubular shaft

metaphysis

part of long bone; connects the epiphysis to the diaphysis

articular (hyaline) cartilage

part of long bone; covers the epiphysis and cushions the opposing bone ends during joint movement

spongy (cancellous) bone

part of long bone; forms an open network of struts and plates in the interior of a bone

compact bone

part of long bone; dense outer layer of bone that forms a sturdy, protective layer

epiphyseal line

part of long bone; where the epiphyseal plate used to be

epiphyseal plate

a disc of hyaline cartilage that grows during childhood to lengthen the bone

periosteum

part of long bone; two-layered membrane that covers the outside of a bone

* richly supplied with nerve fibers, lymphatic vessels and blood vessels

marrow/medullary cavity

part of long bone; central space of the bone

* contains yellow marrow in adults

endosteum

part of long bone; covers the spongy bone in the marrow cavities and lines the canals that pass through compact bone

cortex

part of flat, short and irregular bone; layers of compact bone surrounding the spongy bone in a flat bone

diploe

part of flat, short and irregular bone; internal layer of spongy bone

osteon

part of compact bone; structural unit of compact bone consisting of bone matrix arranged in concentric circles around a central canal

central canal

part of compact bone; contains one or more blood vessels that carry blood through a single osteon

perforating canal

part of compact bone; lie at right angles to the long axis of bone and connect the blood and nerve supply to osteons deeper in the bone and to tissues of the marrow cavity

canaliculi

part of compact bone; connect the lacunae to each other and allows osteocytes to communicate through the hard bone matrix

trabeculae

part of spongy bone; a honeycomb of small needle-like or flat pieces

osteoblasts

cell in bone tissue; produce new bone matrix

osetocytes

cell in bone tissue; mature bone cells that maintain the bone matrix

osteoclasts

cell in bone tissue; giant cells that remove bone matrix by secreting protein-digesting enzymes

osteoprogenitor cells

cell in bone tissue; mesenchymal stem cells that divide and can differentiate into osteoblasts

* maintain populations of osteoblasts and are important in the repair of a fracture

hydroxyapatite

inroganic material in bone matrix

substances that make up hydroxyapatite

calcium and phosphate

function of hydroxyapatite

makes the bone hard and brittle

collagen fibers

organic material in bone matrix

function of collagen fibers

make the bone flexible and able to withstand twisting/bending